I have a 1993 Chevrolet Caprice with Police package. I was driving it and when I came to a stop light it started shaking and jerking. When I got home and turned it off, it would not crank again. It was as if it wasn't getting fuel. So, I changed the fuel filter, fuel pump, rotor, distrubutor cap, spark plugs, and fuel pump relay and still nothing. Does anyone have an idea what it might be?